Transfer fuel pump



Sept.-28, 1937.v .1. F. HoFFER 2,094,171

TRANSFER FUEL PUMP Filed May l, 1955 2 Sheets-Sheet 1 EEE-E,

/ 02 l/azo NVENTOR. J'dmes F Hoffen Sept. 28, 1937. J. F. HoFFER TRANSFER FUEL PUMP Filed May 1, 19:55 2 sheets-sheet 2 INVENTOR.

Jde 2:.' Hoffen BYV ATTORNEY.

' uNrrlail) STATES 'i' ce* o TRANSFER James F. Hofier,k Detroih meh-assigner to Iix-Cell-O Corporatioma corporation Michf igan m Application May '1, 1933;;se'r'1'1? Nu.- ,tsa'ios c claims ionica-31) ence -to lthe accompanying drawings, and then claimed, having the above and other objects in view. l f f In the accompanying drawings whichillustrate This invention relates to, pumpingV ,mechanisms and particularly `to that type'thereof i11-v cludinga reciprocating piston, the 'principal object being the provision of a pump of this type that is simple in construction, efficient in opera- 'tion and which offers the advantages o fa 'rotary type of pump whilel eliminating certain l disadvantages thereof.

Other objects include the provision of a single throughout the several different views: L

Fig. 1 is a more-or-less diagrammatic side ele- `vational view of an internal combustion engine having mounted thereon a pump` constructed in piston reciprocating type of pump by means of which a substantially constant discharge presaccordance with the present invention, to illussure may be maintained upon the fluid fbeing trate one use thereof.

pumped; the provision of' a single piston re-A ciprocating type of pump in which a substantially constant discharge pressure may be maintained upon the fluid being pumped regardless of the position or direction of travel .of the piston; the provision of a single piston reciprocating type of pump in which the pressure of the uid discharged thereby is maintained substantially constant during all stagesof movement lof the pump 'piston regardless of the quantity of fluid re"-` quired to be delivered by the pump as long assuch quantity is not in.l excess of that for which the 'pump is designed to deliver;

Other objects include the provisions` of a pump having a reciprocablecpistonA resiliently urged in one ldirection and an independently yre r ciprocable plungeradapted to positively move i taken centrally through the pump shown in Fig. 1 in-alplane parallel to the paper, and as -.on the line 2-2 of Fig; 3.

shown in Fig. 2, taken' from the left hand end thereof. t

Fig. 4 is a fragmentary sectional view taken on the line 4--4 of Fig. 2.`

modified form of construction, and Fig. Gis a view similar to Figs. 2

ing 'another modified form of construction.

Pumps of the character embodying the presof uses and are particularly4 desirable for use where a pump is required to deliver a fluid `at suitable embodiments ofthe present invention and in which like numerals refer to like parts Fig. 2 is: an enlarged.`vertical vsectional' view Fig. 3 is an end elevational View of the -punip entinventio'n are adaptable to a wide varietyl Fig. 5 isa view similartowFig.' 2 showing'a y and5 show- I I the piston ini opposition to the resilient means, varying volume but at a substantially constant the plunger being adapted to displace liquid from pressure. The construction of the pump will be the cylinder when itis moving toward the piston explained in connection with but` one` of its after its construction for this connection is'made and relative to it. I

A further object of the present invention is the provision of a pumping mechanism including a, cylinder having a one-way inlet at 'one end thereof and an outlet, a piston reciprocable between the inlet and outlet, a one-way by-pass 4adapted to by-pass'fluid from the inlet end of 40 the piston to the outlet end thereof, and a member projecting through the outlet end of the cylinderadapted to move the piston in at least one direction and so reducing the effective cross-r sectional area of the discharge end of the piston that when the piston is moved toward the inlet end .of the cylinder the Volume of liquidl displaced from the inlet end of the cylinder through the by-pass to the outletend of the cylinder is in excess Aof the volume created between theoutlet "o end of the cylinder and the outlet end of the piston during such movement.

The above being among the objects of the present invention, the same consists of certain novel features of construction and combinations of parts to be hereinafter described with refersuch modifications in -the, structure described necessary to meet any' change in conditions caused thereby, will be readily appareiitl to those skilled in the art. f

The particular ,application of the present .invention which `will be described is in connection with its use on internal combustion enginesof the fuel injection type, chief among which are those types of engines commonly known as Diesel engines embodying the compression ignition principle of operation. Accordingly,

2 0 of the Diesel type cylinders (not shown) enclosed within the casing thereof,each of the cylinders being provided upon the side of the engine 20 is afuel'injection pumpindicated generally as at 24, which may be of' any suitable type such asis commonly ern- 5 ployed in connection with such known, its application to other specificuses, and

with a fuel injection valve 22. Suitably mounted engines and which there is indicated generally in Fig. 1, an engine and presumed to have four i at la moderate is connected by individual .tubes 26A to each of the fuel injection valves 22, the pump 24 being so arranged and constructed `as to deliverfto each of the valves 22 a metered quantity of fuel at high pressure and at timed intervals as is well understood in the art. driven in timed relation with the engine 20 in any suitable or conventional manner.

In engines in the type described, it is conventional practice to provide what is commonly known as a transfer pump for drawing fuel-from a source of supply and supplying it to the pump 24 pressure which may be, for instance, twenty pounds per square inch.y In the present instance, the present invention is illustrated as being'incorporated in such a transfer pump and such pumpsis indicated generally in Fig. 1 at 28 and as being suitably secured as by bolts 23 to the side of the injection pump from which it is driven 30 provided within the pump 24 although, as will be readily recognized, any other suitable lmeans` for effecting reciprocation of the pump plunger to be hereinafter described will sumce in any case. 'I'he pump 28 is illustrated as being provided with a suction` line 32 connecting it with a supply tank 34 for the engine fuel, and with a discharge line 36 connecting it with the suction side of the fuel injection pump 24. The pump 28 is also provided with an overflow line 3 8 connected with the tank 34 and through which any excess in the desired amount of fuel pumped isl returned to the tank 34 in a manner which will be described in detail later.

' Referring now to Figs. 2, 3 and 4 and particuularly to Fig. 2, it will be noted that the pump 28 includes a body or casing 40, shown as of cast construction, in which is formed a cylinder 42 opening upon one end thereof. The open endl of the cylinder 42 is threaded for cooperative engagement with the plug 44 whichlserves as aclosure therefor, the plug,being providedl with a central opening or aperture 46 therethrough in which one end of the suction line 32 is adapted to be threably secured. The opposite end of the body 40 is provided with a bore 48 of less diameter than the cylinder 42 and. concentric therewith.

Reciprocably received within the cylinder 42 is a piston 50 shown as a skirted type of piston for the purpose of enabling it to partially receive within it th'e compression spring 52 which constantly urges it to the right as viewed in Fig. 2. The spring 52 is constantly maintained under compression between a `shoulder 54 formed interiorly of the piston 50 adjacent the head thereof and the outwardly extending flange 56 of a plug member 58 received within the cylinder 42. 'I'he flange 56 is received within the enlargement 60 of the opening 46 in the plug 44 which thus provides a shoulder 62 against which it may seat and against which it is maintained by the compressive force of the spring 52. 'I'he right hand end of the plug 58 isextended in close proximity 'in Fig. 2, for the purpose of reducing the effective clearance volume in the cylinder as much as I possible.

'I'he left`hand end of the plug 58 is bored' out to provide a blind opening 64 therein in. whichl is partially received a ball 66 constantly urged toward its seat 68 provided .at the junction between the shoulder 62 and the smaller portion The pump 24 may be by means of a cam or eccentricy the piston is in its exvinder 42 with the opening of the opening 46, by means of the compression spring 10. The right handA end of the compression spring '10 is guided about the *projecting end l of a smaller plug 12 secured within the plug 58 centrally of its hollow end and which plug 12 not only serves to additionally reduce the effective clearance volume in the cylinder 42 'but also serves to limit the distance which the ball valve 66 may lift from its seat 68. As will be observed, the-ball valve 66 servesas a check valve for.. permitting ilow of fuel through thel opening 46 in the direction of the cylinder 42 only. It may be noted at this point that the purpose of making the piston 50 of the skirt type and providing the plugs 58 and 12 to reduce the effective volume in .the cylinder is to permit a greater suction eii'ect to be built up in the pump and thereby enable the pump to lift the fuel' through a greater height ble under certain conditions.

,f Reciprocably received within the bore 48 is a pump plunger or tappet 13 providedat its outery projecting end with an enlarged head 14 which is adapted for engagement with the cam or eccentric 30 of the pump 24 as indicated in a's to be reciprocated thereby.. Preferably, a spring 16 surrounds the extension 18 of the casing 40 provided at the right hand end thereof, as viewed in Fig. 2, and through which the bore` 48 centrally extends, and is maintained under compression between the shoulder formed on the casing and the head 14 of the plunger 13 so as toconstantly urge the head 14'to the right into contact with the cam or eccentric 30. "Ihe use of the spring 16, while desirable, is not necessary in all cases for it will be apparent that the spring 52 in urging the piston `50 to the right will, when in contact with the plunger 13., urge the plunger 13 in the same direction and, as will hereinafter be apparent, whenever the plunger 13 separates from the piston 50 the pressure of the uid at the right hand end of the piston 50 will itself serve to force the plunger 13 outwardly into contact with the carri` 30.

' The head end of the cylinder 42, or the right hand end thereof as viewed in Figs. 2 and 4, is slightly counter-bored as at 82 and intermediate its opposite ends the cylinder` 42 is annularly recessed as at 84. As indicated in Fig. 2, the piston 50 is provided with one' or more openings 86 in 'Ihe annular recess 84 in the cylinder 42 com-v municates through an opening 92 with a larger opening or passage 94 opening onto an exterior wall of the casing 40 and normally closed by a plug 96. A shoulder or seat 98 is formed at the junctionof the-openings 92 and 94 and against which a ball check lvalve |00 is constantly urged by means of a compression spring |02 maintained under compression between the ball |00 and the inner end of the plug 96. A passage |08 connects the counter-bored head portion of the cyl- 94 outwardly of the ball`l00. Another passageI I0 connects the counterbored portion 82 of the cylinder 42 with a larger passage ||2 opening onto an exterior face of the casing 40 and normally closed by a plug ||4. A shoulder 6 is formed at the junction than would otherwise be possi- A- 20 Fig. l soA of the passages and ||2 which forms a seat by the distance traveled. Accordingly, it willbe for a ballvalve ||8 constantly urged thereagainst by the spring |20 constantly maintained under compression between the ball ||8 and the plug ||4. 'I'he passage ||2 outwardly of theball ||8 communicates through a passage |22v with an annular recess |24 formed in the bore 48 midway bctween the ends thereof and, as indicated in Fig. 4, the recessA |24 communicates by a passage |26 with anv opening |28v in the casing 40 in which an end of the overflow` pipe 38 shown in Fig. l is threadably secured. As best indicated in Fig. 4, a passage |30 connects the undercut portion 82 at the head of the cylinder 42 with an opening |32 in which an end of the discharge tube 36 is adapted to be threadably secured.,

It may be desirable, before proceeding with the description of the operation of the pump, to point out that the balls 66 and |00 serve solely as check valves and, accordingly, their respective springs and |02 need be only of sufhcient strength vto 'maintain the operativeness of theirrespective balls. 'I'he ball I8, in addition to functioning as a check valve, 'also serves the purpose of limiting the maximum pressure which may be built up in the pump and, accordingly, the strength of the corresponding spring |20 must be such as to insure its functioning to maintain its seat whenever the discharge pressure `of the pump does not exceed the desired ligure.v Also for reasons which will hereinafter be more apparent, the relative strength of` the spring `|20A should be slightly greater than that of the spring 52 so that the pressure on the discharge side of the pump built up solely by movement of the piston 50 under the influence of the spring 52 will not be suilicient to raise the valve ||8 off its seat.

In the operation vof the pump 28A itwill be apparent that the spring 52 constantly urges the piston 50 to the right as viewed in Fig. 2, and that the head 14 of the pump plunger 13 will be constantly pressed against the Lcam 30 which, in

rotating, will cause reciprocation of the plunger 13. Upon reciprocation of the plunger 13 tothe left, as viewed in Fig. 2, and considering the piston 50 as contacting with the plunger 1'3, the piston 50 will be moved to the left against the com-- pression of the spring, 52. When the piston -50 moves to the right from such position under the influence of the spring 52, it Will create a suction within the cylinder 42 .at its left hand end which will cause the ball valve66 to be lifted from its seat and allow fuel to be drawn into the cylinder 42 through thesuction line 32. When the piston Anext moves to the left under the influence of the plunger 13, abportion of the fuel which has thus been drawn into theleft hand end of the cylinder 42 will be placed under compression by the piston 50 and a portion of it will flow out through the openings 86 into .the annular recess 84, into the opening 92 and will force the check valve |00 off g of its seat. The fuel which thus flows past the rcheck valve |00 will ow into the passage 94 and thence through the passage |08 to the head end apparent that upon movementy of the piston 60 to the left', as viewed in Fig. 2, under the influence of the plunger 13, a greater volume of fuel will be forced from ythe left hand side of the piston to the right handlside thereof than there is .volume at the right hand side thereof to accommodate it. ConsequentlyA this fuel at the right hand end ofthe piston 5.0 will be placed underfpressure, vand if the requirement of the fuel injection pump 24 at such time is not sumcient to use this excess in the volume of fuel passed to the right hand end of the cylinder, such quantity of such excess in excess of the requirement ofthe fuel injection pump 24 will be forced out past the check valve ||8 into the passages ||2 and |22 to the recess |24 from which it will ilow through` the passage |26 and opening |28 to the overflow pipe 38A and be discharged backto the -fuel tank 34.

Inasmuch as the pump 28 is preferably designed to meet the requirements of the pump 24 under all conditions, such excess in the amount of fuel required by the pump 24 will constantly be present and; accordingly, a more or less constant ilow of `fuel through the overflow line 38 back to the tank 34 will continue during 'operation of the engine althoughthe amount of vsuch overflow will, of course, vary in accordance with the needs of the engine and the respective capacities of the pumps 24 and 28. It might also be noted at this point that it is desirable .to return such excess fuel to the tank rather than to the intake side of the pump so as to eliminate any possibility of any air that might be picked up by the overflowing fuel from being carried into the pump. At the same time it may be noted that in carrying such excess fuel back to the supply tank 34 through'tlie recess |24 in the bore 48 for the plunger 413 any fuel that may tend to leak from the cylinder along the plunger 13 will be collected in the recess |24 which is under atmospheric pressure and be carried back rto the supply tank 34. Accordingly, this construction also serves as a means for limiting the leakage of fuel from the pump.

Upon return of the pump plunger 13 to the right, as viewed in Fig. -2, the spring 52 of course tends to cause the piston/50to follow the plunger 13 so as to maintainits contact therewith. The spring 52, however, is proportioned so. as to exert throughv the'piston 50 onthe fuel at' the right hand end of the Ipiston the discharge pressure which it is desired to maintain on the discharge f side of the pump. Accordingly, itwill be apparent that Where the requirement of the' fuel injection pump 24 is not as great as would be rprovided by a movement of the piston 50 to the right at 'a sufficient speed to maintain in contact with the plunger 13, such movement vof the piston 50 to the right will be retarded and the plunger13 will pull away from it. This has the effect of increasing the available volume for reception of the fuel at the right hand end of the piston 50, thus permitting a relatively greater' movement of the piston to the right'than would otherwise be possible in order.l to maintain the proper pressure upon the fuel at such end of the piston. However,

under the conditions assumed the left hand end f ofthe plunger 13 will actually separate from the right hand end of the piston during such movement. Accordingly, upon the next reversal of movement, of the plunger 13 it will move to the leftl -such excess tobe discharged out valve I |8 and back to the tank 34.

is designed to deliver. y

' construction. A y 4 'The right hand end of the cylinder |42 is pro-i of fuel displaced by the plunger 13 is in excess of the requirement of the injection pump 24, the pressure on the fuel at the right hand end of thev cylinder 42 will be raised sufficiently to permit past the ball From the above it will be4 apparent that Awith they above described structure there is a constant tendency to build up pressure on the fuel at the right hand or head end of the piston 50, and consequently at the outlet of theV pump,` regardless of the direction of movement or position of the pis-A ton 50, and that a substantially constant pressure 'will be maintained on the fuel at the discharge side of the pump regardless of any variation in the amount of fuel being pumped as long as such amount is not in excess of that which the pump Referring now to Fig. 5.a modified form of the abovedescribed transfer pump is shown asincluding a casing |40 in which is formed a cylinder bore |42 and a tappetl or plunger bore |44 in' which is received a piston |46`and tappet or plunger |48 respectively. j The left yhand end of the cylinder |42 is closed by an apertured plug |50 corresponding tothe plug 44 previously described and within the left hand end of the cylinder 42 is received a displacement plug |52 corresponding with the plug 58 in the previously described construction and enclosing a spring |54 urging a ball check valve |56 constantly `toward its seat. A spring |58 corresponding to spring 52 in the previously described construction coopcrates to hold the plug member |52 in position and to urge the piston |46 constantly toward the right as viewedin the figure. The cylinder |42 is medially recessed as at |60 and communicates through the opening |62 with a passage |64 normally closed by the ball check valve |66, the passage |64 communicating through the vpassage |68 with the cylinder |42 'at' the right hand end. thereof in substantially the same manneras described in` connection` with the` corresponding parts and passages in the previously described vided with a discharge passage |10 but, instead of vproviding a spring pressed check valve for limiting the maximum pressure which may be built up on the discharge side of the pump, as in the previously described construction, in the present case the maximum pressurecapable of being built up in the pump is controlled by the provision of an'. elastic or variable volume chamber connectedy with the discharge side of the pump and serving as a reservoir for any excess in the amount of fuel pumped and delivering such amounts thereof back to thel pump as may be necessary to maintain the discharge pressure constant and to eliminate pulsations and surges. While such cham- .ber may take any one-of a number of conventional forms such as, for instance, an air bell or dome, a flexible metallic bellows or other like means, as a means of illustration in the present case the' head end or right hand end of the cylinder |42 connects by a passage |12 with a cylinder |14 `in which is-slidably received a piston |16 constantly urged ina downwardly direction bymeans of the compression spring |18 maintained under compression between the head of the piston |16 and the plug |80 closing the open end of the sion spring 2|2.

cylinder. In order to take care of any leakage past the piston |16; the upper end of the-cylinder |14 communicates through passages |82 and |84 with amedial recess |86 in the bore |44 which may be drained back to the supply tank in a manner similar to that described in connectiony with thefsame parts-and passages of the previously described construction.

It will be apparent that the structure described in connection lwith Fig. 5 will operate in substantially the same manner as theconsytruction previouslydescribed except that any excess in the amount of fuel displaced by the piston |46 or plunger |48 over the simultaneous requirement of the fuel injection pump 24 willincrease the pressure on such yfuel and cause suflicient movement of the piston |16 in the cylinder |14 to compensate for such added volume without substan- 'charge side ofthe pump. Otherwise the operation and characteristics of the pump described in connection with Fig. 5 are identical to the construction previously described.

In the construction illustrated in Fig. 6 a body member is provided with a cylinder bore |92 in which 'is reciprocably received a piston |94. `The right hand end of the casing or body member |90 is provided with a smaller bore |96 in which a plungerl or tappet member |98 is reciprocably received. 'Ihe right hand end of the casing |90 is also provided with a pump discharge passage 200 and the bore |96 is provided with an annular recess 202 in connection with'a'passage 204 for conveying away any leakage of fuel about the plunger` |98.

In this modication instead of by-passing the fuel from one side of the piston to the other through passages formed in the casing itself, the left hand end of the piston is recessed so as to threadably receive"` therein the plug member 206 which is axially apertured so as to provide a shoulder or seat 208 against which the ball valve 2 I0 isf-constant1y urged by means of the compreston |94 toward thel right asviewed in the figure.

The auxiliary piston 2 I8 is axially apertured therethrough and formed to provide a valve seat 224 against'which a check valve 226 is constantly urged by means of a compression spring 228. The left hand end of the auxiliary cylinder 2 I6 is provided with an intake opening 230 and received 'within this end of the auxiliary cylinder 2 I6 is a compression spring 232 normally maintaining the piston 2 I8 in spaced relation to such end.

With this construction illustrated in Fig. 6,

movement of the tappet |98 and pistonl |94 causes a pumping action on the fuel in the pump in substantially the same manner as that described in the previously describedconstructions. However, with this construction in case the plunger |98 displaces a greater volume of. fuel at the right .hand end of the piston |94 than-is required for the simultaneous need of the fuel injection pump, such excess in displacement will The bore of the plug 206comforce the piston |94 to the left and the fuel to the left of the piston |94 thus displaced thereby will act against the auxiliary piston ZIB and force it to the left against the compression of the spring 232 to compensate therefor. Accordingly, it will be observed that the auxiliary cylinder 2 6 in this construction function in substantially the same manner and for the same purposes as the cylinder |14 and piston |16 in Fig. 5.

With the above disclosure before them and an understandingof the construction and operation of the structures herein described, it will of course be obvious to those skilled in the art that many variations in the constructions disclosed may be made to effect the same results and, accordingly, vit will be understood that formal changes may be made in the specific embodiments of the invention described without departing from the spirit or substance of the broad invention, the scope of which is commensurate with the appended claims.

I claim:

1. In a pump structure for liquids, in combination a casing provided with a bore and an inlet and outlet therefor, a skirted piston reciprocable in said bore and provided with an opening in the skirt thereof, the open end of said skirt communicating with the inlet end of said bore, said casing having a passage formed therein connecting the outlet end of. said bore with said bore intermediate the ends thereof and in a position to register with said opening in said skirt, and a check valve in said passage limiting the flow of iiuid therethrough to one direction only.

2. In a pump structure for liquids, in combination, a casing provided with a bore and an inlet and outlet therefor, a skirted piston recipro- `cable in said bore and provided with an opening in the skirt thereof, theopen end of said skirt opening toward the inlet end of said bore, said casing having a passage formed therein connecting the outlet end of said bore with said bore intermediate the ends thereof and in a. position to register with said opening in said skirt, a, check valve in said passage limiting the ilow of iluid therethrough to one direction only, means for positively moving said piston in one direction, and resilient means constantly urging said piston in the opposite direction.

3. In a pump structure, in combination, a cylinder having an inlet at one end, a piston in said cylinder, a second piston between said inlet and the iirst piston and spaced from the latter, resilient means for urging said second piston toward the first piston, a discharge outlet adapted y to receive fluid discharged from the space between said pistons, means for moving said firstmentioned piston toward said second piston for discharging fluid from said outlet, said second piston being adapted to move toward said inlet against the action of said last-mentioned resilient means in response to excess pressure between said pistons to relieve said pressure, and a one-way valve in said second piston'adapted to permit llow from said inlet into the space between said pistons.

4. In a pump structure, in combination, a cylinder having an inlet at one end, a piston reciprocable in said cylinder, an outlet in constant communication with the opposite end of the cylinder, a passageway connecting said outlet with the cylinder on the inlet side of said piston, a one-way valve in said passage adapted to permit iiow from the inlet end of the cylinder into the passageway, resilient means constantly urging said piston toward said opposite end of the cylinder, a plunger reciprocable independently of said piston projecting into said opposite end of the cylinder and adapted to move said piston against the urge of said resilient means when moving in opposition to said resilient means, a second piston located between the inlet and said rst piston, resilient means for urging said second piston toward the rst piston, said second piston being adapted to move toward said inlet in response to excess pressure between said pistons to relieve said pressure, and a one-way valve in said second piston adapted to permit ow of fluid from said inlet into the space between said pistons.

JAMES F. HOFFER. 

